Analog Devices Inc. 110855-HMC424LH5

Overview

HMC424LH5 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC 6-bit digital attenuator in a hermetic SMT package, providing 0.5 dB LSB steps across DC–13 GHz with ≤3.8 dB typical insertion loss at 8 GHz and ±0.4 dB + 4% attenuation accuracy for states up to 16.5 dB. It serves as a precision RF signal level control device in high-reliability microwave front-ends.

For engineers reviewing the HMC424LH5 datasheet, HMC424LH5 pinout, HMC424LH5 application, or HMC424LH5 equivalent, key selection criteria include its DC–13 GHz bandwidth, -5 V single-bias operation, 31.5 dB total attenuation range, ±0.3 dB typical bit error, and MIL-PRF-38535 Class B/S screening capability for space and defense systems.

Technical Context

The HMC424LH5 implements a broadband distributed attenuator architecture using GaAs FET switches per bit, enabling DC-coupled operation with 50 Ω matched RF ports (RF1/RF2). Its six independent TTL-compatible control inputs (V1–V6) toggle between 0 V and –5 V to select attenuation states without requiring external level-shifting circuitry.

It features a single –5 V bias supply (Vee), supports 22 dBm input power for 0.1 dB compression, delivers +32 dBm IIP3 in attenuated states, and achieves <50 ns switching time (tON/tOFF) across full frequency range - critical for fast-hopping radar and test instrumentation.

Key Specifications

Pinout & Package

Hermetic ceramic SMT package, 5 mm × 5 mm × 1.2 mm (25 mm²), leadless with exposed ground paddle; RoHS-compliant and compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital RF attenuator applications.

Compared with HMC624LP4E and PE43711, the HMC424LH5 uniquely combines DC–13 GHz bandwidth, hermetic packaging, MIL screening, and –5 V single-rail bias - making it the only option qualified for space-grade phased arrays and hardened military ECM systems.

Availability

HMC424LH5 is available at Aetrix Electronics and suitable for telecom infrastructure, military radar, space systems, and test instrumentation requiring stable component supply across extended lifecycle programs.

Supply support for HMC424LH5 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices acquired Hittite Microwave in 2014 and integrates its high-frequency RF portfolio into precision signal processing solutions for defense, aerospace, and communications.

The HMC424LH5 belongs to Analog Devices' legacy Hittite GaAs MMIC digital attenuator family, engineered specifically for ultra-wideband, high-linearity, and high-reliability RF front-end applications.

FAQ

What is the maximum RF input power rating for the HMC424LH5?

The HMC424LH5 has an absolute maximum RF input power rating of +25 dBm across 0.5–13 GHz. For continuous operation, the datasheet specifies +22 dBm input power for 0.1 dB compression at 1–13 GHz, ensuring linear behavior in most system-level deployments. Derating is recommended above +22 dBm to maintain specified IIP3 and step accuracy. The HMC424LH5 must be operated within these limits to avoid permanent damage or parameter shift.

Does the HMC424LH5 require external blocking capacitors on RF1 and RF2?

Yes, the HMC424LH5 requires external DC-blocking capacitors on RF1 and RF2 if the connected RF line has non-zero DC potential, as both ports are DC-coupled and internally matched to 50 Ω. The datasheet explicitly states that blocking capacitors are mandatory unless the RF source/load is at 0 V DC. Failure to implement them risks bias disruption and degraded return loss. The HMC424LH5's DC coupling is a design feature enabling baseband use, not an omission.

What is the purpose of the exposed ground paddle on the HMC424LH5 package?

The exposed ground paddle on the HMC424LH5 serves dual thermal and RF grounding functions: it lowers thermal resistance (344 °C/W) to dissipate up to 180 mW, and provides low-inductance RF return path for all internal FETs and transmission lines. Per the datasheet, pads 8, 10, 12, and the paddle must be soldered directly to the PCB ground plane using ≥6 thermal vias. Omitting this compromises both reliability and RF performance - especially return loss and isolation above 8 GHz. The HMC424LH5's hermetic package relies on this mechanical interface for specification compliance.

Can the HMC424LH5 operate with positive control voltages instead of –5 V logic?

No, the HMC424LH5 requires negative control voltages: V1–V6 must swing between 0 V (logic low) and –5 V (logic high), with Vee fixed at –5 V ±10%. Its GaAs FET architecture is inherently depletion-mode and incompatible with positive logic families like CMOS or TTL without level-shifting. The datasheet specifies "Low = 0 to –3 V @ 35 μA" and "High = Vee to Vee + 0.8 V", confirming strict negative-rail operation. Using positive voltages will prevent proper bit activation and may damage the HMC424LH5.

Is the HMC424LH5 pin-compatible with other Hittite digital attenuators like the HMC306MS8G?

No, the HMC424LH5 is not pin-compatible with the HMC306MS8G. The HMC424LH5 uses a 12-pin leadless ceramic package with dedicated RF1/RF2, six control inputs (V1–V6), three GND pins, and one Vee pin - while the HMC306MS8G is an 8-pin SOIC with different pin assignment, bias scheme (dual supply), and 5-bit architecture. No documentation or datasheet indicates pin-to-pin equivalence. Substituting the HMC424LH5 for the HMC306MS8G requires full PCB redesign. The HMC424LH5's unique pinout is defined in its outline drawing and pin description table.